The moon is full and Sammy’s cat BB (Princess Buttermilk Biscuit) has disappeared again. Where does she go? Will she come back?

Sammy follows BB up a moonbeam to a magical world. She meets Selena and explores some of the wonders of Selena’s castle. The fun turns to gloom when Sammy learns that BB may not be going home.

Rushing through a door that seems to lead to a crystal garden, Sammy finds herself alone in a dark, cold place. She finds her way back to her friends and the garden, but has a hard decision to make.